使用 Mockito 测试 Java 的行为增强

2022-01-14 00:00:00 unit-testing for-loop mockito java

我想测试一个使用 Mockito 对其进行了增强的 java 方法.问题是当我不知道如何为增强的工作设定期望时.以下代码来自 mockito google 组中未回答的问题:

I want to test a java method that has an enhanced for on it using Mockito. The problem is that when I don't know how to set the expectations for the enhanced for to work. The following code was gotten from an unanswered question in the mockito google group: 

import static org.mockito.Mockito.when;
import static org.testng.Assert.assertTrue;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.mockito.Mockito;
import org.testng.annotations.Test;

public class ListTest
{

  @Test
  public void test()
  {
    List<String> mockList = Mockito.mock(List.class);
    Iterator<String> mockIterator = Mockito.mock(Iterator.class);

    when(mockList.iterator()).thenReturn(mockIter);
    when(mockIter.hasNext()).thenReturn(true).thenReturn(false);
    when(mockIter.next()).thenReturn("A");

    boolean flag = false;
    for(String s : mockList) {
        flag = true;
    }
    assertTrue(flag);
  }
}

for 循环内的代码永远不会被执行.为迭代器设置期望不起作用，因为 java 增强的 for 内部不使用列表迭代器.设置对 List.get() 方法的期望也没有，因为增强的实现似乎也没有调用列表的 get() 方法.

The code inside the for loop never gets executed. Setting expectations for an iterator doesn't work, because the java enhanced for doesn't use the list iterator internally. Setting expectations for List.get() method doesn't either since the enhanced for implementation doesn't seem to call the get() method of the list either.

任何帮助将不胜感激.

推荐答案

模拟迭代器对我有用.请参阅下面的代码示例:

Mocking the iterator works for me. See below code sample:

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import java.util.Collection;
import java.util.Iterator;

import org.junit.Before;
import org.junit.Test;

public class TestMockedIterator {

    private Collection<String> fruits;
    private Iterator<String> fruitIterator;

    @SuppressWarnings("unchecked")
    @Before
    public void setUp() {
        fruitIterator = mock(Iterator.class);
        when(fruitIterator.hasNext()).thenReturn(true, true, true, false);
            when(fruitIterator.next()).thenReturn("Apple")
            .thenReturn("Banana").thenReturn("Pear");

        fruits = mock(Collection.class);
        when(fruits.iterator()).thenReturn(fruitIterator);
    }

    @Test
    public void test() {
        int iterations = 0;
        for (String fruit : fruits) {
            iterations++;
        }
        assertEquals(3, iterations);
    }
}

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